89 Dakota 3.9 2WD. Pump is leaking. The spare I have is identical in every aspect expect for; the return tube is downward instead of upward and the backside lower right corner does not have a provision for the threaded stud. No hole at all. Can I swap the new guts into the old reservoir or can I drill a hole in the new one expecting a threaded hole in the pump??

use the old reservoir

Swapped new pump into old reservoir. Now I have a leak at the pressure fitting on the pump. I tightened that nut down and put a new hose. Yes, o ring on the hose. O rings on the pump. So pissed. Went from one leak to another. I test fitted the hose to the pump prior to install and it would not thread. The fitting had a brass insert inside. I swapped fittings with the one that had no brass insert. Is that my problem?